Microstructures, Mechanical and Electrochemical Properties of Monbta-Based Refractory Multi-component Alloys

Abstract

In order to explore the influence of Cr, V, Ti, and Zr elements and homogenization treatment on MoNbTa-based refractory high-entropy alloys, four alloys, MoNbTaCrV, MoNbTaZrV, MoNbTaTiV and MoNbTaTiZr are prepared in this work. The microstructures, mechanical properties, and corrosion resistance of as-cast and homogenized MoNbTa-based alloys have been analyzed by using x-ray diffraction, scanning electron microscopy, mechanical performance testing, and electrochemical corrosion. The results showed that, except for the MoNbTaZrV alloy, the other three alloys were composed of BCC-phase solid solutions. The metastable phase structure in MoNbTa-based high-entropy alloys can be eliminated by homogenization treatment. Typically (Mo, Nb, Ta)-rich dendritic and (Cr, V, Zr, Ti)-rich interdendritic morphologies were observed. The addition of Ti was very helpful in improving the compressive strain of the alloys. The as-cast MoNbTaTiZr alloy, which showed the compressive strength of 1620 MPa and fracture strain of 22.03%, had the best compression performance. There was still a slight increase after homogenization treatment at 900°C. When the V element was added, the MoNbTa-based alloys had better corrosion resistance. The homogenization treatment had a poor effect on the corrosion resistance.